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This article in JEQ

  1. Vol. 37 No. 4, p. 1536-1545
     
    Received: Jan 17, 2007


    * Corresponding author(s): mario.malagoli@unipd.it
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doi:10.2134/jeq2007.0032

Interactions between Chromium and Sulfur Metabolism in Brassica juncea

  1. Michela Schiavona,
  2. Elizabeth A.H. Pilon-Smitsb,
  3. Markus Wirtzc,
  4. Rüdiger Hellc and
  5. Mario Malagoli *a
  1. a Dep. of Agricultural Biotechnology, Univ. of Padua, Agripolis, 35020 Legnaro PD, Italy
    b Biology Dep., Colorado State Univ., Fort Collins, CO 80523
    c Inst. of Plant Sciences, Univ. of Heidelberg, 69120 Heidelberg, Germany

Abstract

The effects of chromate on sulfate uptake and assimilation were investigated in the accumulator Brassica juncea (L.) Czern. Seven-day-old plants were grown for 2 d under the following combination of sulfate and chromate concentration: (i) no sulfate and no chromate (−S), (ii) no sulfate and 0.2 mmol L−1 chromate (−S +Cr), (iii) 1 mmol L−1 sulfate and no chromate (+S), or (iv) 1 mmol L−1 sulfate and 0.2 mmol L−1 chromate (+S +Cr). Despite the toxic effects exerted by chromate as indicated by altered level of reducing sugars and proteins in leaves, the growth of B. juncea was only weakly reduced by chromate, and no variation in chlorophyll a and b was measured, regardless of S availability. Chromium (Cr) was stored more in roots than in leaves, and the maximum Cr accumulation was measured in −S +Cr plants. The significant decrease of the sulfate uptake rates observed in Cr-treated plants was accompanied by a repression of the root low-affinity sulfate transporter (BjST1), suggesting that the transport of chromate in B. juncea may involve sulfate carriers. Once absorbed, chromate induced genes involved in sulfate assimilation (ATP-sulfurylase: atps6; APS-reductase: apsr2; Glutathione synthethase: gsh2) and accumulation of cysteine and glutathione, which may suggest that these reduced S compounds play a role in Cr tolerance. Together, our findings indicate that when phytoremediation technologies are used to recover Cr-contaminated areas, the concentration of sulfate in the plant growth medium must be considered because it may influence the ability of plants to accumulate and tolerate Cr.

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Copyright © 2008. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyAmerican Society of Agronomy, Crop Science Society of America, and Soil Science Society of America